Ellobius Lutescens Research Articles

How voles adapt to subterranean lifestyle: Insights from RNA-seq

Life under the earth surface is highly challenging and associated with a number of morphological, physiological and behavioral modifications. Subterranean niche protects animals from predators, fluctuations in environmental parameters, but is characterized by high levels of carbon dioxide and low levels of oxygen and implies high energy requirements associated with burrowing. Moreover, it lacks most of the sensory inputs available above ground. The current study describes results from RNA-seq analysis of four subterranean voles from subfamily Arvicolinae:Prometheomys schaposchnikowi,Ellobius lutescens,Terricola subterraneus, andLasiopodomys mandarinus. Original RNA-seq data were obtained for eight species, for nine species, SRA data were downloaded from the NCBI SRA database. Additionally assembled transcriptomes of Mynomes ochrogaster and Cricetulus griseus were included in the analysis. We searched for the selection signatures and parallel amino acid substitutions in a total of 19 species. Even within this limited data set, we found significant changes ofdN/dSratio by free-ratio model analysis for subterranean Arvicolinae. Parallel substitutions were detected in genesRAD23BandPYCR2. These genes are associated with DNA repair processes and response to oxidative stress. Similar substitutions were discovered in theRAD23genes for highly specialized subterraneanHeterocephalus glaberandFukomys damarensis. The most pronounced signatures of adaptive evolution related to subterranean niche within species of Arvicolinae subfamily were detected forEllobius lutescens. Our results suggest that genomic adaptations can occur very quickly so far as the amount of selection signatures was found to be compliant with the degree of specialization to the subterranean niche and independent from the evolutionary age of the taxon. We found that the number of genomic signatures of selection does not depend on the age of the taxon, but is positively correlated with the degree of specialization to the subterranean niche.

Signatures of Adaptation in Mitochondrial Genomes of Palearctic Subterranean Voles (Arvicolinae, Rodentia).

This study evaluates signatures of selection in the evolution of the mitochondrial DNA of voles, subfamily Arvicolinae, during the colonization of subterranean environments. The comparative sequence analysis of mitochondrial protein-coding genes of eight subterranean vole species (Prometheomys schaposchnikowi, three species of the genus Ellobius: Ellobius talpinus, Ellobius fuscocapillus and Ellobius lutescens, two species of the genus Terricola: Terricola subterraneus and Terricola daghestanicus, Lasiopodomys mandarinus, and Hyperacrius fertilis) and their closest aboveground relatives was applied using codon-substitution models. The highest number of selection signatures was detected in genes ATP8 and CYTB. The relaxation of selection was observed in most mitochondrial DNA protein-coding genes for subterranean species. The largest amount of relaxed genes is discovered in mole voles (genus Ellobius). The number of selection signatures was found to be independent of the evolutionary age of the lineage but fits the degree of specialization to the subterranean niche. The common trends of selective pressures were observed among the evolutionary ancient and highly specialized subterranean rodent families and phylogenetically young lineages of voles. It suggests that the signatures of adaptation in individual mitochondrial protein-coding genes associated with the colonization of the subterranean niche may appear within a rather short evolutionary timespan.

Distinguishing between three modern Ellobius species (Rodentia, Mammalia) and identification of fossil Ellobius from Kaldar Cave (Iran) using geometric morphometric analyses of the first lower molar

Ellobius remains are common and often abundant in southeastern Europe, western and central Asia archaeological sites. A correct identification of species is crucial for our understanding of the evolution of species and communities through time, including biostratigraphic sequences to be established. This study applies geometric morphometric methods (GMM) to Ellobius first lower molars, with the objectives: 1) to discriminate modern species and explore morphological and size differences in reference samples; and 2) to identify fossil specimens recovered in archaeological sites, based on the aforementioned analysis. The reference dataset used in this paper includes specimens belonging to the three species that today occur in the southeastern Europe, western and central Asia: Ellobius fuscocapillus, E. lutescens and E. talpinus. The archaeological material comes from Late Pleistocene Iranian site of Kaldar Cave (Khorramabad valley, Lorestan Province, western Iran). Our study shows that the shape of the anterior cap and the arrangement of the following triangles allow discriminating the three studied extant Ellobius species. The shapes of E. fuscocapillus and E. lutescens m1 appear rather similar, whereas Ellobius talpinus is well separated from these two species. The total length and the anterior cap of m1 in E. fuscocapillus is greater than in Ellobius lutescens. The GMM analyses performed on the modern reference dataset allowed us to identify fossil specimens from Kaldar Cave as E. lutescens and some as E. fuscocapillus, and excluding E. talpinus.

The complete mitochondrial genomes of three Ellobius mole vole species (Rodentia: Arvicolinae)

The subterranean voles of the genus Ellobius are species of subfamily Arvicolinae well adapted to underground life. In this paper, we report the assemblies of complete mitochondrial genomes for three mole voles from genus Ellobius – northern mole vole Ellobius talpinus (16,376 bp), transcaucasian mole vole E. lutescens (16,540 bp), and southern mole vole E. fuscocapillus (16,388 bp). Each of three mitogenomes encode for 12S and 16S rRNAs, 22 tRNAs, 13 protein-coding genes, and D-loop in the characteristic arrangement of subfamily Arvicolinae (Rodentia: Cricetidae). This study verifies the evolutionary status of subgenera Bramus and Ellobius within the genus Ellobius at the molecular level. The mitochondrial genome would be a significant supplement for the Ellobius genetic background. The three Ellobius species formed a monophyletic group with the high bootstrap value (100%) in all examinations.

Geographic variation in the skull morphology of Ellobius lutescens Thomas, 1897 (Mammalia: Rodentia) by geometric morphometric analyses

In this study, we examined a total of 43 samples belonging to three Ellobius lutescens populations from Turkey, Iran and Nakhchivan, which are geographically separated by the Zagros, Tendürek and Alborz mountain ranges. We applied geometric morphometric methods (GMMs) to explore the differences in size and shape of the cranium and mandible. Indeed, we intriguingly found that the populations differed in cranium but not mandible size. Comparison of the Iranian and Turkish populations alone revealed morphological differences in the shape of the cranium and mandible that could be used as a barometer to predict the origin of individual animals. Importantly, our findings indicate that the Zagros and Tendürek mountain ranges may have acted as a barrier between these two populations, resulting in evolutionary divergence in these anatomical features. Consequently, we propose that within E. lutescens, subspecies including E. lutescens woosnami exists and in time, genetic, besides geographical barriers, may prevent subspecies from interbreeding with each other.

Endogenous amdoparvovirus-related elements reveal insights into the biology and evolution of vertebrate parvoviruses

Amdoparvoviruses (family Parvoviridae: genus Amdoparvovirus) infect carnivores, and are a major cause of morbidity and mortality in farmed animals. In this study, we systematically screened animal genomes to identify endogenous parvoviral elements (EPVs) disclosing a high degree of similarity to amdoparvoviruses, and investigated their genomic, phylogenetic and protein structural features. We report the first examples of full-length, amdoparvovirus-derived EPVs in the genome of the Transcaucasian mole vole (Ellobius lutescens). We also identify four EPVs in mammal and reptile genomes that are intermediate between amdoparvoviruses and their sister genus (Protoparvovirus) in terms of their phylogenetic placement and genomic features. In particular, we identify a genome-length EPV in the genome of a pit viper (Protobothrops mucrosquamatus) that is more similar to a protoparvovirus than an amdoparvovirus in terms of its phylogenetic placement and the structural features of its capsid protein (as revealed by homology modeling), yet exhibits characteristically amdoparvovirus-like genome features including: (1) a putative middle ORF gene; (2) a capsid gene that lacks a phospholipase A2 domain; (3) a genome structure consistent with an amdoparvovirus-like mechanism of capsid gene expression. Our findings indicate that amdoparvovirus host range extends to rodents, and that parvovirus lineages possessing a mixture of proto- and amdoparvovirus-like characteristics have circulated in the past. In addition, we show that EPV sequences in the mole vole and pit viper encode intact, expressible replicase genes that have potentially been co-opted or exapted in these host species.

Brain Sexual Differentiation and Requirement of SRY: Why or Why Not?

Brain sexual differentiation is orchestrated by precise coordination of sex steroid hormones. In some species, programming of select male brain regions is dependent upon aromatization of testosterone to estrogen. In mammals, these hormones surge during the organizational and activational periods that occur during perinatal development and adulthood, respectively. In various fish and reptiles, incubation temperature during a critical embryonic period results in male or female sexual differentiation, but this can be overridden in males by early exposure to estrogenic chemicals. Testes development in mammals requires a Y chromosome and testis determining gene SRY (in humans)/Sry (all other therian mammals), although there are notable exceptions. Two species of spiny rats: Amami spiny rat (Tokudaia osimensis) and Tokunoshima spiny rat (Tokudaia tokunoshimensis) and two species of mole voles (Ellobius lutescens and Ellobius tancrei), lack a Y chromosome/Sry and possess an XO chromosome system in both sexes. Such rodent species, prototherians (monotremes, who also lack Sry), and fish and reptile species that demonstrate temperature sex determination (TSD) seemingly call into question the requirement of Sry for brain sexual differentiation. This review will consider brain regions expressing SRY/Sry in humans and rodents, respectively, and potential roles of SRY/Sry in the brain will be discussed. The evidence from various taxa disputing the requirement of Sry for brain sexual differentiation in mammals (therians and prototherians) and certain fish and reptilian species will be examined. A comparative approach to address this question may elucidate other genes, pathways, and epigenetic modifications stimulating brain sexual differentiation in vertebrate species, including humans.

Genomes of Ellobius species provide insight into the evolutionary dynamics of mammalian sex chromosomes.

The X and Y sex chromosomes of placental mammals show hallmarks of a tumultuous evolutionary past. The X Chromosome has a rich and conserved gene content, while the Y Chromosome has lost most of its genes. In the Transcaucasian mole vole Ellobius lutescens, the Y Chromosome including Sry has been lost, and both females and males have a 17,X diploid karyotype. Similarly, the closely related Ellobius talpinus, has a 54,XX karyotype in both females and males. Here, we report the sequencing and assembly of the E. lutescens and E. talpinus genomes. The results indicate that the loss of the Y Chromosome in E. lutescens and E. talpinus occurred in two independent events. Four functional homologs of mouse Y-Chromosomal genes were detected in both female and male E. lutescens, of which three were also detected in the E. talpinus genome. One of these is Eif2s3y, known as the only Y-derived gene that is crucial for successful male meiosis. Female and male E. lutescens can carry one and the same X Chromosome with a largely conserved gene content, including all genes known to function in X Chromosome inactivation. The availability of the genomes of these mole vole species provides unique models to study the dynamics of sex chromosome evolution.

Review of unique odd chromosome-numbered underground rodent species ofthe Palearctic region: Ellobius lutescens Thomas 1897 (Rodentia: Cricetidae)

A review of the species within the genus Ellobius from Turkey is provided. The Transcaucasian mole vole, Ellobius lutescens, is the westernmost representative of the genus and among the most enigmatic and yet most neglected of the Palearctic placental mammals. Currently, its distribution is thought to be restricted to eastern Anatolia. The Transcaucasian mole voles inhabit a wide variety of habitats across this distribution area in semiarid or grassland territories and high-elevation cultivated fields. The species' distribution, feeding ecology, population structure, behavior, reproduction, genetics, and fossil records are reviewed here for Turkey. This paper brings together information published during the last century in books and scientific papers. Future research needs to include collation of further data on population dynamics, maximum length of the breeding season, reliable abundance estimates, and studies of distribution and migration. Other areas worthy of investigation are the identification of wintering areas, acquisition of up-to-date data on reproduction and mortality, and investigations into the consequences of environmental changes for the species.

Rodent Fauna of the Middle Paleolithic Cave Site Taglar (Transcaucasus): Paleoecology and Environment

Rodent fauna from the well-known cave site Taglar (Middle Paleolithic), located in Karabakh (Transcaucasus) is described. The species composition includes Allactaga williamsi, Meriones libycus, Cricetulus migratorius Ellobius lutescens, Arvicola terrestris and Microtus (Microtus) obscurus. Some archaic characters in water vole teeth morphology were revealed. Data of cave site Taglar are compared with rodent fauna of unique Mousterian cave site Azych (Transcaucasus). The ecological features of rodent fauna refl ect the predominance of arid steppe-like and even semidesert-like landscapes near the site. The fauna most probably corresponds to the megainterstadial of the last glaciation (MIS 3). The new data elucidate species composition of rodents of Transcaucasus during the warm stage of last glaciations and the environments surrounding this unique Mousterian cave site of ancient humans.

Reproduction, postnatal development, and social behavior of Ellobius lutescens Thomas, 1897 (Mammalia: Rodentia) in captivity

The reproduction, postnatal development, and social behaviors of the Transcaucasian mole vole (Ellobius lutescens) were studied in the laboratory in 2012/2013. The collected voles were kept in glass cages in captivity conditions and observations were made throughout the year. The litter size, gestation period, neonate weight, eye-opening, weaning, and earliest sexual maturity age were observed. Pups were born with 'nipple-seizing incisors'. These incisors were different from those of adults. The molars and normal incisor eruption appeared after 19-21 days. Females have three pairs of nipples. The adult females were bigger in size than the males, yet the males consumed more food than the females. Isolated individuals consumed more food than did the paired animals.

Serologic Survey of Plague in Animals, Western Iran

Serologic Survey of Plague in Animals, Western Iran

Sox9 gene regulation and the loss of the XY/XX sex-determining mechanism in the mole vole Ellobius lutescens.

In most mammals, the Y chromosomal Sry gene initiates testis formation within the bipotential gonad, resulting in male development. SRY is a transcription factor and together with SF1 it directly up-regulates the expression of the pivotal sex-determining gene Sox9 via a 1.3-kb cis-regulatory element (TESCO) which contains an evolutionarily conserved region (ECR) of 180bp. Remarkably, several rodent species appear to determine sex in the absence of Sry and a Y chromosome, including the mole voles Ellobius lutescens and Ellobius tancrei, whereas Ellobius fuscocapillus of the same genus retained Sry. The sex-determining mechanisms in the Sry-negative species remain elusive. We have cloned and sequenced 1.1kb of E. lutescens TESCO which shares 75% sequence identity with mouse TESCO indicating that testicular Sox9 expression in E. lutescens might still be regulated via TESCO. We have also cloned and sequenced the ECRs of E. tancrei and E. fuscocapillus. While the three Ellobius ECRs are highly similar (94-97% sequence identity), they all display a 14-bp deletion (Δ14) removing a highly conserved SOX/TCF site. Introducing Δ14 into mouse TESCO increased both basal activity and SF1-mediated activation of TESCO in HEK293T cells. We propose a model whereby Δ14 may have triggered up-regulation of Sox9 in XX gonads leading to destabilization of the XY/XX sex-determining mechanism in Ellobius. E. lutescens/E. tancrei and E. fuscocapillus could have independently stabilized their sex determination mechanisms by Sry-independent and Sry-dependent approaches, respectively.

Klebsiella oxytoca: opportunistic infections in laboratory rodents

Opportunistic pathogens have become increasingly relevant as the causative agents of clinical disease and pathological lesions in laboratory animals. This study was conducted to evaluate the role of Klebsiella oxytoca as an opportunistic pathogen in laboratory rodents. Therefore, K. oxytoca-induced lesions were studied from 2004 to early 2006 in naturally infected rodent colonies maintained at The Jackson Laboratory (TJL), Bar Harbor, USA, the Animal Research Centre (Tierforschungszentrum, TFZ) of the University of Ulm, Germany and the Central Animal Facility (ZTM) of the Hannover Medical School, Germany. K. oxytoca infections were observed in substrains of C3H/HeJ mice, which carry the Tlr4(Lps-d) allele; in LEW.1AR1-iddm rats, the latter being prone to diabetes mellitus; in immunodeficient NMRI-Foxn1(nu) mice; and in mole voles, Ellobius lutescens. The main lesions observed were severe suppurative otitis media, urogenital tract infections and pneumonia. Bacteriological examination revealed K. oxytoca as monocultures in all cases. Clonality analysis performed on strains isolated at the ZTM and TFZ (serotyping, pulse field gel electrophoresis [PFGE], enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction, sequencing of 16S rRNA and rpoB genes) revealed that the majority of bacteria belonged to two clones, one in each facility, expressing the capsule type K55 (ZTM) or K72 (TFZ). Two strains, one isolated at the ZTM and one at the TFZ, showed different PFGE and ERIC pattern than all other isolates and both expressed capsule type K35. In conclusion, K. oxytoca is an opportunistic pathogen capable of inducing pathological lesions in different rodent species.

Chromosomal evolution of Arvicolinae (Cricetidae, Rodentia). II. The genome homology of two mole voles (genus Ellobius), the field vole and golden hamster revealed by comparative chromosome painting

Using cross-species chromosome painting, we have carried out a comprehensive comparison of the karyotypes of two Ellobius species with unusual sex determination systems: the Transcaucasian mole vole, Ellobius lutescens (2n = 17, X in both sexes), and the northern mole vole, Ellobius talpinus (2n = 54, XX in both sexes). Both Ellobius species have highly rearranged karyotypes. The chromosomal paints from the field vole (Microtus agrestis) detected, in total, 34 and 32 homologous autosomal regions in E. lutescens and E. talpinus karyotypes, respectively. No difference in hybridization pattern of the X paint (as well as Y paint) probes on male and female chromosomes was discovered. The set of golden hamster (Mesocricetus auratus) chromosomal painting probes revealed 44 and 43 homologous autosomal regions in E. lutescens and E. talpinus karyotypes, respectively. A comparative chromosome map was established based on the results of cross-species chromosome painting and a hypothetical ancestral Ellobius karyotype was reconstructed. A considerable number of rearrangements were detected; 31 and 7 fusion/fission rearrangements differentiated the karyotypes of E. lutescens and E. talpinus from the ancestral Ellobius karyotype. It seems that inversions have played a minor role in the genome evolution of these Ellobius species.

Characterization of Pisrt1/Foxl2 in Ellobius lutescens and exclusion as sex-determining genes

The rodent Ellobius lutescens is an exceptional mammal which determines male sex constitutively without the SRY gene and, therefore, may serve as an animal model for human 46,XX female-to-male sex reversal. It was suggested that other factors of the network of sex-determining genes determine maleness in these animals. However, some sex-determining genes like SOX9 and SF1 have already been excluded by segregation analysis as primary sex-determining factors in E. lutescens. In this work, we have cloned and characterized two genes of the PIS (polled intersex syndrome) gene interval, which were reported as candidates in female-to-male sex reversal in hornless goats recently. The genes Foxl2 and Pisrt1 from that interval were identified in E. lutescens DNA and mapped to Chromosome 8. We have excluded linkage of Foxl2 and Pisrt1 loci with the sex of the animals. Hence, the involvement of this gene region in sex determination may be specific for goats and is not a general mechanism of XX sex reversal or XX male sex determination.

The sex determination in Ellobius lutescens remains bizarre

Mammalian sex determination and gonad differentiation are the result of a complex interaction of fine-tuned spatial and temporal gene expression with threshold levels of individual genes. The male pathway is initiated by SRY. Some exceptional mammals determine male sex without the SRY gene and even without a Y chromosome. Ellobius lutescens in this report is one example of this “weird” species. We provide key data on the genomic level that there are no coarse differences in the genomes of male and female animals by comparative genomic hybridization. On the gene level we studied the gene Nr5a1 for the orphan nuclear receptor, steroidogenic factor SF-1, a central constituent for gonad differentiation and adrenal gland development. The Ellobius lutescens Nr5a1 gene was mapped to the proximal short arm of chromosome 2 by fluorescence in situ hybridization. In addition, we provide evidence by linkage analysis in two E. lutescens pedigrees that Nr5a1 is not the key male sex-determining gene in Ellobius lutescens.

On distribution, morphology and biology of the Mole Vole, Ellobius lutescens Thomas, 1897 (Mammalia: Rodentia) in eastern Turkey

Ellobius lutescens reaches the western limit of its distribution in Turkey, and is confined there to a relatively small area in the eastern part of the country near the borders with Iran and Iraq, from where new records are provided (Hakkari: Yüksekova). The species lives in family groups and excavates underground tunnels by scratching the soil with the incisors and pushing the loosened soil behind the body with the fore and hind limbs. Mole Voles are vegetarian and forage in underground burrow systems. They feed primarily on large subterranean edible parts of plants. Both sexes have an apparently identical karyotype (2n = 17, NF = 34). The karyotype consists of 8 pairs of biarmed autosomes and a single small submetacentric chromosome. Both sexes have the chromosome constitution XO. Some biological and morphological peculiarities are discussed.

Exclusion of SOX9 as the Testis Determining Factor in Ellobius lutescens: Evidence for Another Testis Determining Gene Besides SRY and SOX9

In mammals the initiation of testis determination usually depends on the Y-chromosomal gene SRY. A few species, however, escape from this rule with a testis determination that is independent of SRY. The mole vole Ellobius lutescens is one of these species. It is not known how testis determination is initiated in this species but it has been suggested that a gene from the sex determination cascade usually acting downstream of SRY is mutated and has taken over the testis-determining function. At present SOX9 is the only candidate gene for which a testis-determining function in the absence of SRY has been observed. To test the hypothesis that testis differentiation in E. lutescens is initiated by SOX9, segregation analysis of SOX9 alleles was performed in an E. lutescens family. As there is no marker data available in this species we screened both Ellobius SOX9 introns for polymorphisms suitable for segregation studies. A biallelic polymorphism was found in the second intron of the SOX9 gene and analysis of this marker in the Ellobius family revealed an inheritance pattern completely independent of the sex of the animals. Thus, SOX9 can be excluded from being the testis-determining factor in E. lutescens. These results provide evidence for another possibly yet unknown gene besides SRY and SOX9 able to exert testis-determining function.

Morphological and Karyological Pecularities of the Species Ellobius lutescens Thomas, 1897 (Rodentia: Cricetidae) in Turkey

Six animals of the species Ellobius lutescens Thomas, 1897 were studied morphologically and with conventional and G-chromosome banding techniques. The animals were collected from Ovapİnar, 50 km north of Van-Turkey. Skins and skulls have been deposited at the Dicle University, Science and Art Faculty, Biology Department. Morphological characters, measurements and karyological pecularities were compared with previously published accounts. The diploid number was found to be 2n=17. The karyotype consisted of 7 pairs submeta/subtelosentric and one pair of metasentric chromosomes. A single submetasentric X chromosome was also found. Results show that the samples are not Ellobius fuscocapillus, but instead belong to Ellobius lutescens Thomas 1897.